1. Field of Invention
This invention relates to energetic cavities. Specifically, the present invention relates to miniature cavities equipped with energetic material.
2. Description of the Related Art
Miniature cavities, such as explosives-filled microcavities and nanocavities, are employed in various demanding applications including micro thrusters, safe-and-arm devices, and airbag initiators. Such applications require versatile, highly controllable, and cost-effective cavities with specific blast characteristics.
Some existing microcavity actuators include explosives-filled cavities etched in silicon. A polysilicon bridge wire detonator is often positioned on top of the explosives-filled microcavity. Bridge wires are resistive heating wires designed to detonate an accompanying charge disposed in a microcavity actuator. The bridge wires require precise positioning relative to the charge to ensure detonation. Accurate and expensive manufacturing processes are often required to ensure precise positioning of the charge relative to the heater. These stringent positioning requirements may increase actuator costs and dud rates.
Conventional silicon-based microcavity actuators, which are often called initiators or thrusters, depending on their application, often require relatively high-temperature manufacturing processes. Consequently, temperature-sensitive applications, such as integrated circuit applications, are often incompatible with the microcavity actuators. Furthermore, these microcavity actuators often require a rigid silicon substrate, which severely limits actuator versatility and applicability. In addition, requisite construction materials and microcavity processing steps often necessitate vertical cavity sidewalls. Vertical cavity sidewalls may yield undesirable blast characteristics for some applications.
To enhance blast characteristics, a cavity lined with a conductive heater may be employed, as disclosed in U.S. Pat. No. 6,105, 503, by Baginski, issued Aug. 22, 2000, entitled ELECTRO-EXPLOSIVE DEVICE WITH SHAPED PRIMARY CHARGE. However, device design constraints necessitate a rigid silicon substrate, which may require either expensive reactive ion etching or high-temperature manufacturing steps that are incompatible with many applications. Furthermore, these cavities typically require an electrical path through the substrate, which is problematic, especially in applications requiring special substrates, such as Integrated Circuit (IC) applications.
Hence, a need exists in the art for a versatile, reliable, and cost-effective cavity actuator that is suitable for use with various substrates, including temperature-sensitive substrates, and provides optimum blast characteristics for a given application. There exists a further need for efficient systems enabled by these miniature cavities.